The general objective is to determine how a weak humoral immune response can enhance tumor growth. To pursue this objective we will: (1) confirm that antibodies against cell surface antigens of tumor cells stimulate growth of the tumor cells; 2) determine the specificity of the immune response, i.e. are the antibodies specific for tumor cell antigens, or are they species-specific antigens, or histocompatibility antigens; 3) determine the role of membrane transport in mediating the immune response of tumor cells. We will determine if specific membrane transport systems are stimulated, and what kinetic characteristics of the system are altered.